**Core Concept**
The Medical Termination of Pregnancy (MTP) Act regulates the conditions under which a pregnancy can be terminated. The act specifies the requirements for the opinion of medical practitioners to ensure that the termination is carried out legally and safely.

**Why the Correct Answer is Right**
The MTP Act mandates that for pregnancies between 12 and 20 weeks, the opinion of two medical practitioners is required to confirm that the continuation of the pregnancy would involve a risk to the life or health of the pregnant woman, or there is a substantial risk that if the child were born, it would suffer from such physical or mental abnormalities as to be seriously handicapped.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the MTP Act allows for the termination of pregnancy with the opinion of one doctor up to 12 weeks.
**Option B:** This option is also incorrect as it does not align with the stipulated gestational age limits set by the MTP Act.

**Clinical Pearl / High-Yield Fact**
It's crucial to remember that the MTP Act has specific gestational age limits for the termination of pregnancy, and the number of medical practitioners' opinions required changes based on these limits.

**Correct Answer:** D. between 12 and 20 weeks